Choice A is the correct answer. Diagonal lines.

1. Diagonal ($m eq 0$): Goes up and down forever. Range is $(-\infty, \infty)$.
2. Horizontal ($y=5$): Range is just $\{5\}$.
3. Vertical ($x=3$): Range is $(-\infty, \infty)$ but it's not a function.

💡 Strategic Tip: Any non-horizontal linear function covers all y-values.

Choice B is incorrect.Choice C is incorrect because not a function. Choice D is incorrect.